A Three-Dimensional Guide for Using the Octant Rule When a student is first acquainted with the octant rule,' one of his prime difficulties is visualizing haw planes A and B pass through a cyclic ketone. His usual aid is a two-dimensional drawing of a three-dimensional figure which is not very helpful. A partial solution is to use molecular models.* We have found that if models are used and planes constructed which can he placed into the models, the student can mare readily decide which groups are coplanar and which are not and to which quadrant a cantributing group belongs. Our first attempts were made using cardboard (model a t top in the photograph). After modifying the cardboard planes several times, plastic planes were constructed (model a t bottom in the photograph). There is no difficulty in adding plane C which is perpendicular to planes A and B and intersects the carhon-oxygen double bond (half of a carbon-carbon bond in our models) a t midpoint. A to-scale template for use with Fieser models and assembly directions can be obtained by writing to the author.
'
Djerassi, C., "Optical Rotatory Dispersion," McGraw-Hill Book Company, New Yark, New York, 1960. *Pasto, D. J., and Johnson, C. R., "Organic Structure Determination," Prentice-Hall, Inc., Englewood Cliffs, NewJersey, 1969, p. 234.
The College of Wooster
LeRoy W. Haynes
Wooster, Ohio 44691
Volume 57. Number 11. November 1974
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